Below is a summary of the support request for your records:

Issue Description:

User reported where in Power automate flow taking far too long to complete the flow.

Resolution:

• Apply to each action execute sequentially by default and if you have more than 200, 300 items to loop it will take a lot of time to execute.
• We can change this sequential running to parallel running by enabling concurrency control.
• If we enable concurrency control on Apply to each action, then this action will execute more rapidly, and our flow will take less time to run.
• Just I have added sample screenshots to understand better.